chore(commands): Remove duplicate commands from context/commands/

### Removed
- context/commands/create-agent.md (canonical: .claude/commands/context/agent/create.md)
- context/commands/find-mcp-servers.md (canonical: .claude/commands/context/mcp/search.md)
- context/commands/promote-skill.md (canonical: .claude/commands/context/skill/promote.md)
- context/commands/refine-skill.md (canonical: .claude/commands/context/skill/refine.md)
- context/commands/research-plugin-components.md (canonical: .claude/commands/context/plugin/research.md)
- context/commands/create-lang-conversion-skill.md (canonical: .claude/commands/create-lang-conversion-skill.md)
- context/commands/validate-lang-conversion-skill.md (canonical: .claude/commands/validate-lang-conversion-skill.md)

### Notes
- Remaining context/commands/ files are unique (Homebrew, GHA, Helm, MDBook)
- Completes Phase 8 of command restructuring

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: aRustyDev